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NBRC CRTFree Certified Respiratory Therapist practice test
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10 real NBRC CRT practice questions with instant answers and explanations — no account, no credit card, no email. Score yourself, then unlock the full bank of 500 questions whenever you’re ready. The NBRC CRT passing score is Low cut score of 86/140 scored items (high cut score 92 unlocks RRT eligibility).
A physician orders oxygen via nasal cannula at 4 L/min for a patient with mild hypoxemia. Approximately what FiO2 does this flow rate deliver?
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Q1. A physician orders oxygen via nasal cannula at 4 L/min for a patient with mild hypoxemia. Approximately what FiO2 does this flow rate deliver?
Correct answer: B. 33-37%
Nasal cannula FiO2 rises roughly 4% per liter above room air, so 4 L/min delivers approximately 33-37% FiO2.
Q2. What is the minimum oxygen flow rate needed when using a simple oxygen mask to flush out exhaled carbon dioxide and prevent rebreathing?
Correct answer: B. 5 L/min
Simple masks require a minimum flow of about 5 L/min to flush the mask's internal volume and prevent CO2 rebreathing.
Q3. While a patient uses a non-rebreathing mask, the respiratory therapist notes the reservoir bag collapses almost completely with each inspiration. What should be done?
Correct answer: B. Increase the flow rate
The reservoir bag should remain at least one-third to two-thirds full during inspiration; if it collapses, flow should be increased so the patient does not entrain room air.
Q4. Which oxygen delivery device uses jet mixing to entrain a fixed, predictable proportion of room air regardless of the patient's inspiratory flow demand?
Correct answer: C. Air-entrainment (Venturi) mask
Venturi masks use jet mixing to entrain a fixed ratio of room air, delivering a consistent FiO2 independent of the patient's inspiratory pattern.
Q5. A Venturi mask is set to deliver 40% FiO2 using an air-entrainment ratio of approximately 3:1 (air:oxygen). If the oxygen input flow is 12 L/min, approximately what total flow is delivered to the patient?
Correct answer: D. 48 L/min
A 3:1 air-to-oxygen ratio means 3 parts air plus 1 part oxygen; total flow equals input flow multiplied by (ratio+1), so 12 L/min x 4 = 48 L/min total flow.
Q6. What is the primary therapeutic goal of bland aerosol therapy delivered with a large-volume nebulizer?
Correct answer: B. Add humidity/moisture to help mobilize secretions
Bland aerosol (sterile water or saline) therapy adds humidity to the airway to help thin and mobilize secretions; it contains no medication.
Q7. Why is a heated humidifier typically used when a patient receives continuous supplemental oxygen at high flow rates through a nasal cannula or mask?
Correct answer: B. To prevent drying of the nasal and airway mucosa from the dry medical gas
Medical gases are essentially anhydrous; heated humidification adds moisture and warmth to prevent mucosal drying and irritation during prolonged or high-flow oxygen therapy.
Q8. A patient with an artificial airway (endotracheal tube) requires humidification of inspired gases. Why is this especially critical compared to a patient breathing through an intact upper airway?
Correct answer: B. The upper airway's normal humidifying function is bypassed, so inspired gas is not conditioned before reaching the lower airway
The nose and upper airway normally warm and humidify inhaled air; bypassing them with an artificial airway means inspired gas must be actively conditioned to prevent mucosal damage and secretion inspissation.
Q9. When performing endotracheal suctioning on an adult patient, what is the recommended maximum duration for each suction pass to minimize the risk of hypoxemia?
Correct answer: B. 10-15 seconds
Suction passes should generally be limited to about 10-15 seconds to reduce the risk of hypoxemia, mucosal trauma, and bradycardia.
Q10. How should an oropharyngeal airway (OPA) be properly sized for an adult patient?
Correct answer: B. From the corner of the mouth to the angle of the jaw or earlobe
Correct OPA sizing is measured from the corner of the patient's mouth to the angle of the jaw (or earlobe), approximating the distance needed to hold the tongue off the posterior pharynx.
Exam facts and objectives sourced from the official NBRC (National Board for Respiratory Care) certification page. Last reviewed June 2026.
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